Does 3 blinks on a Rheem furnace mean High Limit Switch or Pressure Switch?

Rheem used two different control board families: on Table A boards (62-24084 Integrated Spark), 3 blinks means Open High Limit Switch and 2 blinks means Pressure Switch Open. On Table B boards (UT / Honeywell 62-24268), 3 blinks means Pressure Switch Open and 4 blinks means High Limit Open. You can tell them apart in 5 seconds: if the main house blower fan is roaring nonstop, 3 blinks is an Open High Limit; if the main house blower is off and only the small exhaust motor runs, 3 blinks is an Open Pressure Switch.

Why does my Rheem Direct Spark Ignition (DSI) furnace click rapidly and lock out on 1 blink?

Many Rheem 80% Criterion II and Classic 90 furnaces use a 62-24141 Direct Spark electrode rather than a glowing igniter. If burners light during the clicking spark and shut off 3 seconds later with 1 blink, buff both the 62-23543-01 remote flame sensor rod and the flat steel burner face under the electrode to restore ground-return microamps.

OEM Control Family: Rheem / Ruud 62-24084 (Table A) & 62-24268 (Table B) • WeatherKing

Rheem & Ruud Furnace Blink Code: 3 Blinks Discrepancy Solved

⚡ Instant OEM Answer (Rheem Table A vs. Table B 3-Blink Rule): Rheem and Ruud use two conflicting 1-digit LED tables: on Table A (62-24084 boards), 2 Blinks = Pressure Switch Open and 3 Blinks = High Limit Open. On Table B (62-24268 UT boards), 3 Blinks = Pressure Switch Open and 4 Blinks = High Limit Open. 5-Second Ear Test: If your main house blower fan roars nonstop, 3 Blinks is a High Limit fault; if the main blower stays off, clear the brass inducer pressure port.

Dual-Table Disambiguation Chart

Side-by-Side Rheem / Ruud Table A vs. Table B Comparison & Part SKUs

Covers Rheem Criterion II, Classic 80/90 Plus, Prestige (RGRA, RGPJ, RGDG, R92PA, R95PA, R801CA), Ruud Silhouette II / Achiever, and WeatherKing furnaces. Newer 7-segment Ruud/Rheem boards use 2-character codes (10 = Lockout, 22/23 = Pressure Switch, 33 = High Limit, 57 = Flame Rollout).

Blink Count	Table A (62-24084 Board)	Table B (62-24268 UT Board)	Rheem OEM Part SKU & Triage Fix
Steady ON	Normal Power / Idle	Normal Power / Idle	Healthy 24VAC control power. Check thermostat heat call.
1 Blink	1-Hr Ignition Lockout	1-Hr Ignition Lockout	Polish `62-23543-01` Flame Sensor or test `62-22868-93` HSI / `62-24141-04` Spark.
2 Blinks	Pressure Switch Open	Pressure Switch Stuck Closed	Ream yellow brass inducer port with paperclip; OEM Switch `42-24196-01` ($38).
3 Blinks	High Limit Switch Open	Pressure Switch Open	Ear Test: Main blower roaring = Limit `47-25349` / Filter; Blower OFF = Brass Port / Trap.
4 Blinks	Auxiliary Blower Limit Open	Primary High Limit Open	Replace dirty air filter immediately; test blower run capacitor `µF`.
5 Blinks	Manual Flame Rollout Open	False Flame Sensed	CRITICAL: Inspect burner vestibule rollout switches (`47-22861-01`) & heat exchanger.
6 Blinks	Reversed Polarity / Internal	Compressor / Rollout Lockout	Verify 120V L1/Neutral polarity and cross-check blower door schematic label.

Other OEM Brand Decoders: Carrier / Bryant Code 31 & 33 → Goodman / Amana (1–7 Flashes) → Trane / American Standard → Lennox Dual Red+Green LED → York / Coleman / Evcon → Nordyne / Mobile Home → Multimeter µA & Ω Guide →